>Has anyone looked at the locking behavior of _Access and _Assign methods? I know for example that the _Assign method will not fire if it changes its own property. I suspect that the property being managed by the _Access or _Assign method cannot be changed while the code is running. Does anyone know if other property values can be changed from outside the object while one property's _Access or _Assign code is running?
>The basic question is how many semaphores does VFP use to control access to object properties (one per object instance, one per class, one per property)?
>
>TIA
>Ned

If I understand your question correctly, this is not an issue. Since VFPs processes are single threaded, a property cannot be changed while code is running. Even COM servers with the apartment threading model still block simultaneous calls, forcing them to run serially.